Sub Form Field Validation ?

Sub Form Field Validation ?

I have a subform where I have set a script for converting the contents of a field to 'Upper Case'
 
input.Product_Description = input.Product_Description.toUpperCase();
 
And when I access the form directly, it works really well - and I can add the script to On Add, On Edit, Validate etc..doenst seem to matter...
 
But when I enter data through a master form, that has the first form embedded as a subform, the field criteria are not inherrited, so the data entered does not get converted to Uppercase....
 
Surely scritping on a form, should be inherrited when it is access as a sub form ?
 
>>>>
My work-around is to add a script to the 'On Add Success' of the main form :
 
for each rec in Multi_Line_New_Products  [ID != 0]
{
    rec.Product_Description = rec.Product_Description.toUpperCase();
}


 
This is ok whilst i have less than 100 records in the database, but if this gets to a 2000 records, it will be needlessly updating all records !